Warm the oil in a large pot over medium heat for one minute. Add the bratwurst and saute until lightly browned. Transfer bratwurst to a bowl and cover with foil to keep warm.

Combine broth, leeks (see below), potatoes and ground pepper in the pot. Cover and bring to a boil. Reduce the heat and simmer until potatoes are tender, approximatley 15 minutes. Transfer half the mixture to a bowl and cover with foil.

Using a potato masher or hand immersion blender, mash the remaining vegetables. Stir in the bratwurst and remaining vegetables. Stir in the red pepper and beer. Simmer for 5-10 minutes more. Top each serving with chopped chives and/or sour-cream.